Frequency generator for machine control systems



J1me 1953 L. E. DE NEERGAARD 2,640,938

FREQUENCY GENERATOR FOR MACHINE CONTROL SYSTEMS Original Filed April 10,1947 v INVENTOR- 2 229 8 Lf/F ae/c DE lvaflesAAeb o 0 22 v|1um11111m1|1m1n BY QZhZPfi w .4 TTOk/VE Y Patented June 2, 1953FREQUENCY GENERATOR FOR MACHINE CONTROL SYSTEMS Leif E. de Neergaard,Bufi'alo, N. Y., assignor to Actrol, Inc., Tuckahoe, N. Y., acorporation of Delaware Application April 10, 1947, Serial No. 740,688,now Patent No. 2,552,622, dated May 15, 1951, which is a division ofapplication Serial No. 460,955, October 6, 1942, now Patent No.2,423,440, dated July 8, 1947. Divided and this application April 27,1951, Serial No. 227,857

4 Claims. 1

The present invention relates to apparatus for generating pulsatingcurrents, and it is particularly adaptable for generating such currentsfor use in the practice of my invention disclosed and claimed in myUnited States Patent No. 2,423,440. This application is a division ofPatent No. 2,552,- 622, a division of the said Patent No. 2,423,440.

An object of the invention is to provide a pulsating current generatorwhich can be moved along an arm for causing a stylus associated with thegenerator to follow the contour of a pattern over which the arm extends,the generator being slidable along the arm and being capable of causingan increase or decrease in the frequency of the pulsations in accordancewith the direction and rate of movement of the generator along the arm.

Another object of the invention is to provide a generator of the typereferred to in which a current is generated having a substantially fixedor a base frequency when the generator is stationary relative to the armand which frequency varies above and below in accordance with the rateand direction of movement of the generator along the arm.

Other objects and advantages of the invention will be apparent from thefollowing description of preferred forms of the invention, referencebeing made to the accompanying drawings wherein:

Fig. 1 is a plan view of a device referred to as a translator, by whichthe movements of a stylus about the outline of a pattern can betranslated into a plurality of electrical pulsating currents;

Fig. 2 is a fragmentary plan view of one arm of the translator;

Fig. 3 is a view of certain parts of the device shown in Fig. 2 but on alarger scale;

Fig. 4 is a view taken substantially on line 4-4 of Fig. 3; and

Fig. 5 is a fragmentary view of an endless tape used in the device shownin Figs. 2 through 4.

In the U. S. Patent 2,423,440 mentioned hereinbefore, I have disclosedand claimed a method by which a machine tool or the like can be operatedfrom a recording of pulsating electric currents to reproduce movementsin the tool, which movements were formerly made by a stylus following apattern or template. In recording the currents, the stylus isoperatively connected with generators and is arranged to move relativeto two or more coordinate axes of a coordinate system. The generatorsare each associated with a respective coordinate of the coordinatesystem,

and they are each adapted to generate a current iii) having a relativelyfixed, or base frequency while the stylus is stationary relative to thecoordinate axes with which the respective generators are associated, andto increase or decrease the frequencies of the current or signalgenerated thereby in accordance with the rate and direction of movementof the stylus relative to the respective coordinates. The recordedfrequencies, including a current having only the base frequency, arereproduced simultaneously and the tool moved along coordinates of asimilar coordinate system in accordance with the variation in therecorded frequencies from the recorded base frequency. The presentinvention is directed to the generators for generating these pulsatingcurrents.

Referring now to Fig. 1, there is shown a translator consisting of abase H5 having a fiat surface upon which a template or pattern I21 maybe placed so that a stylus can be moved about the outline of thepattern. Means, not shown, may be provided for securing the pattern tothe base.

A rod-like fixed arm or support member H6 extends lengthwise of the baseand adjacent one edge thereof, and the ends of member H6 are supportedslightly above the base by two brackets A bracket 220, slidable onmember H6, is provided with an extension 22] to which an arm 222 isattached, the arm extending at 90 from the support rod H6. The fixed armor support H6 and movable arm 222 lie in a plane parallel to the surfaceof the base H5. A bracket or cell carriage 225 similarly is mounted onarm 222. A stylus 226 is formed integral with the bracket 225 and itprojects downwardly to a point adjacent the surface of base I I5 so thatit may closely follow the outline of a template on the surface.

The support H6 and arm 222 correspond to the cordinates of a coordinatesystem and it will be apparent that the stylus 226 can be moved to anypoint over a substantial area of the base H5 by sliding bracket 220along the support H6 and by moving the brackets 225 along the arm 222.By recording simultaneously, the movements of the brackets 220 and 225along their respective supports and reproducing the move ments of thebrackets by corresponding tool controlling elements, the movements ofthe stylus can be reproduced in the tool, as set forth in Patent2,423,440 mentioned hereinbefore.

In order to record the movements of the brackets 220 and 225 I haveprovided a novel generating device, one of which is carried by each ofthe brackets and its associated support arm. The generating devices oneach bracket and support arm are similar, and for the purposes ofillustration, I will refer to the generating device on bracket 225.Reels or pulleys 223 are mounted at opopsite ends of the arm and anendless tape 22! is mounted on the pulleys. The tape 22'! is formed ofan opaque material and is provided with a series of evenly spaced,uniformly wide slots 228 therein, as may be seenin Fig. 5. Preferably,the tape is punctured periodically at 229 for engagement with driveteeth 230 formed on the pulleys 223. One of the pulleys .223, 102ibracket 220, is driven at a constant rate-by a synchronous motor 232throughsuitable driving thephoto-electric-elernent through-theslots/228.

The light beam is substantially the same Width as .the .materialbetween-the slots 228 so that as the tape passes between the bulb andcell, the light .beam will be interruptedcompletely foran instantbetween the presentation .of each slot.

.This interrupted light beam causes a pulsating current orsignal outputto be produced in the circuit'of the light sensitive cell 23-5.This'circuit may-be connected with a recording system similartothatdescribcd in Patent 2,423,440 for :re-

cording the pulsations. It will be apparent that by-movingthe bracket225:along the arm Z'iithe pulsations generated by the photo-eleotriccell 235 will beincreasedand-decreased according to the 'rate anddirectionpf movement. The base frequency of the,generated'current'willbea function-of the speed of the tape and the number of slots in thetape.

It will be understood that a tape 2'41 similar to tape-22? canibeprovided along support :H 6 and a photo-electric Sgenerator 242 similarto :that described'canbemounted on bracket 220 so-th-at-the movements ofthe bracket 226 can be reflected in a;.p ulsating current generated bythe photo-electrio cell. For three dimensional recordings the styluscanbe arranged to .move vertically longitudinallyso that as the stylusrises :and lowers overthe contour of a template-it'wilhcause'variationsin the frequency of theourrent generated in the manner described withreference to the generators on brackets 220 and .1225.

Lhus, by my invention, I have provided 'generators that may ibe readilymounted for movement along members forming coordinates of a coordinatesystem. Although the generators are formed by relatively few parts, theyprovide a pulsating current or signal having a fixed or base frequencywhen the generator is stationary relative to its associated coordinate,but which accurately .increases .or decreases the frequency according tothe direction and rateof movement along its ordinate.

Although I .have described several preferred forms ofxtheinvention,'it'is to beiunderstoodthat other forms :might be adopted,tall :falling within the ,scope-of the claims which follow.

I claim:

1,. A frequency :generator comprising :an arm, a source -,oflightiluxand alight flux responsive element in :fi-xed relation to eachether and translatable along said arm, said element being responsive tovariations in light flux incident .thereon by variations in.anelectrical characteristic of the element, a member extending linearlyparallel to said arm and subject to said light flux,

and means for moving said member with respect 'itOISflidfiIlllySfiidmember having periodically disposedalong its length regions of diversetrans- 'thereby to produce a constant frequency of "change in the saidelectrical characteristic of the element while saidlight source andelement are stationary von said arm and variations from said :frequencycorresponding to motion imparted to said source and element along saidarm.

A frequency generator comprising an arm, a source of light flux and alight flux responsive element 'in fixed relation to each other andtranslatable along "said arm, said-element being responsive tovariations .in light flux incident thereon 'by variations in anelectrical characteristic of "the element, an endless tape havin aportion thereof extending linearly parallel .to said arm and passingbetweensaid light source and said light responsive element, and meansfor movingithe 'said tapeata constantrate with respect to said arm, saidtape having periodically disposedalong its length regions'of diversetransmissibility for said light flux, thereby to produce a-constantfrequency of change 'in the said=electrical characteristic of theelement while said light source andelement are stationary on said armand variations from said frequency corresponding to motion imparted tosaid source and element along-said arm.

3. A frequency generator comprising an arm, a-souroe-of light and alight responsive element in fixed relation 'to each other, said elementbeing responsive to variations of light flux incident thereon byvariations in an electrical characteristic of the element,-ahousingslideably mounted for translation along saidarmenclosing said 'lightsource and 'said light responsive elemerit and mounting "the same insaid fixed relation to eacho'ther, an 'endless tape having a portionthereof extending linearly parallel to said arm and passing through saidhousing between said light source and said light responsive element, andmeans for'moving said tapeata constant rate with respect to said arm,said tape having opaque and light transmitting portions disposedperiodically along its length, thereby to produce a constant frequencyof change in the said electricalcharacteristic'of the element while saidlight source "and element are stationary on said arm and variations fromsaidirequency corresponding to motion imparted to said-source andelement along said arm.

4. A frequency generator comprising an arm, a'source of light and alight responsive element in fixed rel'ation'to eachothensai'delement'being responsive to light flux incident thereon by production ofan'electric current,'a housingslideably mounted for translationalongsaid arm enclosing said light source and said light responsiveelement and mounting the same insaid fixed relation .to :each other, :anendless tape having a per-- tion thereof extending [linearly parallel to:said arm :and :passing "through said housing between said light source:and :said :light :responsive element, and means for moving said tape at:a 13011- stant :rate with respect to :said Farm, said tape ReferencesCited in the file of this patent UNITED STATES PATENTS Number 52,111,013 2,137,024 2,176,828 2,246,496

Name Date Vedder Mar. 15, 1938 Moore et a1 Nov. 15, 1938 Walker Oct.1'7, 1939 Asbury June 24, 1941

